1 00:00:29,520 --> 00:00:31,480 It's morning in the forest. 2 00:00:32,520 --> 00:00:35,120 And for this troop of chimpanzees, 3 00:00:35,200 --> 00:00:37,040 it's time to get out of bed 4 00:00:37,120 --> 00:00:38,960 and get on with the day. 5 00:00:45,960 --> 00:00:49,640 But when you sleep in a nest 40 meters up in the air, 6 00:00:51,080 --> 00:00:53,320 it can be a bit of a challenge. 7 00:01:12,880 --> 00:01:17,120 This morning ritual has been playing out like clockwork 8 00:01:18,560 --> 00:01:20,320 for countless generations. 9 00:01:25,680 --> 00:01:30,240 A rhythm driven by one of the most mysterious properties of our universe. 10 00:01:38,160 --> 00:01:39,000 Time. 11 00:01:41,920 --> 00:01:45,080 And time is playing an extra important role 12 00:01:45,160 --> 00:01:46,800 for one female chimp. 13 00:01:49,320 --> 00:01:51,120 Celeste is in her mid-30s, 14 00:01:52,720 --> 00:01:55,040 and she has a ticking clock inside her. 15 00:01:59,840 --> 00:02:03,840 A clock that was set 13.8 billion years ago. 16 00:02:14,720 --> 00:02:16,800 From The Big Bang came atoms… 17 00:02:20,040 --> 00:02:21,000 …and energy… 18 00:02:22,440 --> 00:02:25,800 …which have journeyed across vast reaches of space. 19 00:02:31,280 --> 00:02:32,760 And these ingredients 20 00:02:34,040 --> 00:02:35,720 are now assembling… 21 00:02:38,520 --> 00:02:40,720 to create a new life. 22 00:02:44,600 --> 00:02:48,760 In Celeste's womb, a tiny chimpanzee is forming. 23 00:02:52,960 --> 00:02:57,320 It will be another 150 days before this baby meets the world. 24 00:02:59,960 --> 00:03:01,440 That's the time it takes. 25 00:03:04,320 --> 00:03:06,120 And without time, 26 00:03:06,200 --> 00:03:09,440 nothing in our universe would ever be born. 27 00:03:12,720 --> 00:03:14,920 From the youngest chimpanzee… 28 00:03:16,920 --> 00:03:18,800 to the oldest black hole. 29 00:03:23,680 --> 00:03:27,280 But how did time start in the first place? 30 00:03:29,240 --> 00:03:32,480 Does everything experience time in the same way? 31 00:03:35,000 --> 00:03:38,440 And will our universe's clock ever stop ticking? 32 00:04:09,440 --> 00:04:12,960 The day begins for a chimp much as it does for us. 33 00:04:16,280 --> 00:04:17,200 Breakfast. 34 00:04:23,680 --> 00:04:27,360 A critical meal… when you're eating for two. 35 00:04:35,800 --> 00:04:38,760 Celeste is already an experienced mom. 36 00:04:42,120 --> 00:04:46,560 Her firstborn, Apollo, is the dominant male of the troop. 37 00:04:48,800 --> 00:04:51,960 And he can be a bit slow to get going in the morning. 38 00:04:59,120 --> 00:05:01,760 Each chimp is a different age. 39 00:05:04,640 --> 00:05:06,960 Each has a distinct personality. 40 00:05:09,720 --> 00:05:13,120 But all of them are creatures of routine. 41 00:05:17,520 --> 00:05:21,920 Their lives governed by the passage of time. 42 00:05:24,520 --> 00:05:25,840 We can't see it. 43 00:05:26,840 --> 00:05:29,040 -Or hear it. 44 00:05:29,840 --> 00:05:32,720 -We can't influence it in any way. 45 00:05:34,240 --> 00:05:39,480 And yet, every heartbeat, every choice and action, 46 00:05:39,560 --> 00:05:45,800 every inaction is a consequence of time's continuous flow. 47 00:05:47,240 --> 00:05:50,400 It can whiz by or drag on. 48 00:05:51,480 --> 00:05:54,040 But time ticks ever onward. 49 00:05:55,320 --> 00:06:00,920 Stars and planets form, age, and die. 50 00:06:02,440 --> 00:06:05,400 In their wake, new stars emerge. 51 00:06:05,480 --> 00:06:07,720 And from a rare few, 52 00:06:07,800 --> 00:06:11,600 the most mysterious objects in the universe are born. 53 00:06:13,120 --> 00:06:14,320 Black holes. 54 00:06:22,040 --> 00:06:24,840 Time is the cosmic conductor. 55 00:06:27,600 --> 00:06:30,520 Nothing can escape its grasp. 56 00:06:44,680 --> 00:06:49,240 Although we have devices that can track and measure time… 57 00:06:54,920 --> 00:06:55,800 …chimps don't. 58 00:07:04,280 --> 00:07:07,800 Celeste and her family use the sun as their guide. 59 00:07:11,800 --> 00:07:14,760 Rising and arcing across the sky. 60 00:07:19,120 --> 00:07:20,040 As it moves… 61 00:07:23,200 --> 00:07:24,080 so do they. 62 00:07:31,960 --> 00:07:35,080 Chimps rarely sleep in the same nest twice. 63 00:07:35,960 --> 00:07:39,040 Each morning, they head off in search of fresh fruit. 64 00:07:41,640 --> 00:07:45,280 Journeying from one part of their territory to another. 65 00:07:49,120 --> 00:07:52,320 But right now, the ripest fruit… 66 00:07:54,840 --> 00:07:57,640 is on the other side of an open plain. 67 00:08:02,480 --> 00:08:06,240 Apollo and the strongest members of the troop go ahead 68 00:08:07,160 --> 00:08:09,480 to make sure it's safe for the others. 69 00:08:12,280 --> 00:08:13,440 Out in the open, 70 00:08:13,520 --> 00:08:17,240 they're vulnerable to predators, rival chimps, 71 00:08:18,160 --> 00:08:20,000 and the heat of the rising sun. 72 00:08:24,160 --> 00:08:25,560 They need to be quick. 73 00:08:26,840 --> 00:08:28,760 Time is ticking. 74 00:08:33,720 --> 00:08:36,920 The sun traveling across the sky 75 00:08:37,000 --> 00:08:39,600 forms the chimps' basic unit of time. 76 00:08:43,680 --> 00:08:47,440 From sunrise to sunset and back to sunrise. 77 00:08:49,520 --> 00:08:51,000 The 24-hour day. 78 00:08:54,200 --> 00:08:57,400 But a day is not actually a measure of time at all. 79 00:08:59,160 --> 00:09:02,200 It's a measure of motion. 80 00:09:08,640 --> 00:09:11,480 As our planet rotates on its axis, 81 00:09:11,560 --> 00:09:18,120 the forest moves through space at 1,600 kilometers per hour. 82 00:09:20,360 --> 00:09:25,400 It takes 24 hours for Earth to do one full turn. 83 00:09:28,280 --> 00:09:32,000 Giving the chimps 24 hours of movement, 84 00:09:33,120 --> 00:09:36,880 12 in sunshine and 12 in darkness. 85 00:09:38,560 --> 00:09:41,680 Again and again. 86 00:09:46,800 --> 00:09:52,080 It's our planet's steady spin that sets Earth's master clock. 87 00:09:55,040 --> 00:09:58,200 And is the chimps' trusted timekeeper. 88 00:10:02,480 --> 00:10:05,080 But this essential cycle we take for granted… 89 00:10:07,320 --> 00:10:08,840 is not universal. 90 00:10:15,840 --> 00:10:18,480 As soon as you leave our home planet… 91 00:10:20,280 --> 00:10:22,960 …the 24-hour day no longer applies. 92 00:10:27,960 --> 00:10:29,840 Flying closest to the sun… 93 00:10:32,080 --> 00:10:33,520 …is the planet Mercury. 94 00:10:35,160 --> 00:10:39,000 Compared to us, it rotates at a snail's pace. 95 00:10:44,520 --> 00:10:49,760 Our neighbor Venus spins even slower. 96 00:10:51,400 --> 00:10:54,200 It takes longer to rotate on its axis 97 00:10:55,520 --> 00:10:57,760 than it does to orbit the sun. 98 00:11:00,920 --> 00:11:06,040 Making Venus's day longer than its year. 99 00:11:09,680 --> 00:11:12,640 Each planet has its own unique day length. 100 00:11:32,320 --> 00:11:36,040 Including planets far beyond our solar system. 101 00:11:40,360 --> 00:11:42,440 Sixty-three light years away, 102 00:11:43,520 --> 00:11:45,280 orbiting a young star, 103 00:11:46,360 --> 00:11:48,640 is Beta Pictoris b. 104 00:11:52,520 --> 00:11:55,240 It spins so fast… 105 00:11:58,720 --> 00:12:01,000 …it bulges out at the sides. 106 00:12:04,720 --> 00:12:08,160 It is the fastest-spinning world we know of. 107 00:12:10,200 --> 00:12:13,120 Here, a day lasts just eight hours. 108 00:12:18,480 --> 00:12:23,120 Every planet in our universe spins at its own speed. 109 00:12:26,360 --> 00:12:27,760 Billions of worlds, 110 00:12:28,880 --> 00:12:30,440 each with their own clock, 111 00:12:31,760 --> 00:12:33,800 ticking away to different rhythms. 112 00:12:35,360 --> 00:12:40,880 But all moving forward on a universal cosmic timeline. 113 00:12:58,560 --> 00:12:59,640 Back on Earth, 114 00:13:00,640 --> 00:13:03,120 with the sun now almost directly overhead, 115 00:13:05,080 --> 00:13:07,560 the chimps know exactly what time it is. 116 00:13:17,160 --> 00:13:18,360 It's lunchtime. 117 00:13:31,160 --> 00:13:35,760 And their crossing of the savanna has been timed to perfection. 118 00:13:42,680 --> 00:13:44,400 They've hit the jackpot. 119 00:13:51,760 --> 00:13:54,680 These sweet berries of the African grape tree 120 00:13:56,400 --> 00:13:58,560 are only around for a few weeks. 121 00:14:05,080 --> 00:14:08,600 A rare seasonal gift from the forest. 122 00:14:12,680 --> 00:14:16,280 Where the middle of the day is a very productive time. 123 00:14:20,840 --> 00:14:24,640 Animals of all sizes are tending to their daily tasks. 124 00:14:30,000 --> 00:14:32,880 And each experiences time differently. 125 00:14:37,120 --> 00:14:40,800 For small creatures that live fast, short lives… 126 00:14:45,600 --> 00:14:48,960 …lunchtime can feel like a lifetime. 127 00:14:54,680 --> 00:14:57,440 For slower, longer living things, 128 00:14:58,120 --> 00:15:01,280 an hour can go by in the blink of an eye. 129 00:15:08,320 --> 00:15:11,360 But whether you're living in high speed 130 00:15:12,360 --> 00:15:14,120 or in slow motion, 131 00:15:15,960 --> 00:15:21,000 all life in the forest must adhere to the same 24-hour day. 132 00:15:23,720 --> 00:15:25,920 And as the world keeps spinning… 133 00:15:29,400 --> 00:15:31,560 …those days keep ticking by… 134 00:15:33,600 --> 00:15:37,720 dictating the lives of every chimpanzee. 135 00:15:41,440 --> 00:15:42,760 One in particular. 136 00:15:49,960 --> 00:15:51,920 At just 15 weeks, 137 00:15:52,880 --> 00:15:56,960 this baby's entire body could fit in its mother's hand. 138 00:16:00,560 --> 00:16:02,440 For it to fully form, 139 00:16:02,520 --> 00:16:05,760 a cascade of perfectly timed events must occur. 140 00:16:08,160 --> 00:16:10,360 For the next 130 days, 141 00:16:11,120 --> 00:16:15,480 every minute, every nanosecond is critical. 142 00:16:24,200 --> 00:16:30,160 New cells divide and grow with remarkable speed and precision. 143 00:16:34,200 --> 00:16:35,200 Right now, 144 00:16:36,160 --> 00:16:41,680 brain cells are multiplying at a rate of around 15 million per hour. 145 00:16:51,760 --> 00:16:54,800 All of us, from our very first moments, 146 00:16:55,800 --> 00:17:00,160 have a deep biological relationship with time. 147 00:17:17,360 --> 00:17:19,120 As the sunlight wanes, 148 00:17:21,760 --> 00:17:24,280 the chimps instinctively switch gears. 149 00:17:27,840 --> 00:17:29,080 To evening mode. 150 00:17:39,120 --> 00:17:41,920 Nesting calls signal to the whole troop. 151 00:17:44,400 --> 00:17:47,560 It's time to find a safe place to spend the night. 152 00:18:01,400 --> 00:18:05,560 Their bedding needs to be soft but strong. 153 00:18:12,200 --> 00:18:14,640 It doesn't hurt if it tastes good either. 154 00:18:18,880 --> 00:18:21,800 The rhythm of every day in the forest 155 00:18:21,880 --> 00:18:25,360 is determined by the sun's position in the sky. 156 00:18:34,560 --> 00:18:37,000 But the chimp's innate sense of time 157 00:18:38,200 --> 00:18:40,920 comes from something inside them. 158 00:18:49,680 --> 00:18:53,680 Deep in their brains is a biological clock. 159 00:18:56,560 --> 00:18:59,520 Bundles of neurons act as a pendulum… 160 00:19:01,840 --> 00:19:06,400 …controlled by genes that switch on and off… 161 00:19:08,520 --> 00:19:12,960 and a cycle that repeats every 24 hours. 162 00:19:16,240 --> 00:19:21,320 These clock genes create a circadian rhythm in the body 163 00:19:22,080 --> 00:19:28,200 that waxes and wanes in sync with our planet's rotation. 164 00:19:30,600 --> 00:19:32,040 Controlling hormones… 165 00:19:36,520 --> 00:19:37,440 …heart rates, 166 00:19:38,800 --> 00:19:40,640 and energy levels. 167 00:19:46,200 --> 00:19:50,760 And right now, the chimps' body clocks are sending the message, 168 00:19:52,160 --> 00:19:54,720 "It's time to get sleepy." 169 00:19:57,960 --> 00:19:59,560 Not everyone can though. 170 00:20:14,320 --> 00:20:17,240 Celeste's baby's brain is still forming. 171 00:20:20,640 --> 00:20:23,000 With no internal clock of its own, 172 00:20:23,640 --> 00:20:27,240 it relies on its mother's hormones to keep it synchronized. 173 00:20:29,600 --> 00:20:33,360 But baby doesn't always get the memo. 174 00:20:37,480 --> 00:20:39,120 Lucky for Celeste, 175 00:20:39,200 --> 00:20:41,560 with so much growing to do, 176 00:20:41,640 --> 00:20:44,520 her baby does eventually drift off. 177 00:20:59,600 --> 00:21:03,520 While the chimps go to sleep high in the treetops… 178 00:21:07,280 --> 00:21:10,680 other forest dwellers are just waking up. 179 00:21:22,720 --> 00:21:25,400 Body clocks tick away 180 00:21:25,480 --> 00:21:29,760 in the cells of plants and animals throughout the forest. 181 00:21:38,320 --> 00:21:43,520 Clock genes evolved two and a half billion years ago 182 00:21:43,600 --> 00:21:45,600 in the first living cells. 183 00:21:48,080 --> 00:21:52,880 Those that could anticipate the light and dark of a day had an advantage. 184 00:21:56,160 --> 00:21:57,920 And as life evolved, 185 00:21:59,240 --> 00:22:01,840 it synchronized to Earth's motion. 186 00:22:02,880 --> 00:22:04,680 So that today, 187 00:22:04,760 --> 00:22:09,400 these clocks exist in almost every creature on Earth. 188 00:22:13,640 --> 00:22:16,440 Although some creatures prefer day and others night… 189 00:22:22,320 --> 00:22:26,200 all life is dancing to the same beat. 190 00:22:28,720 --> 00:22:30,960 Thanks to cellular clocks 191 00:22:31,040 --> 00:22:36,240 that tick in time with the spin of our Earth. 192 00:22:53,000 --> 00:22:55,520 As yesterday becomes a memory… 193 00:22:58,040 --> 00:23:00,440 …another new day begins in the forest. 194 00:23:09,560 --> 00:23:11,000 A fresh cycle, 195 00:23:12,760 --> 00:23:17,160 and yet, no clock can ever truly be reset. 196 00:23:24,720 --> 00:23:29,240 And there are subtle clues all around the forest that reveal why. 197 00:23:32,440 --> 00:23:38,040 Nothing is the same today as it was yesterday. 198 00:23:42,200 --> 00:23:44,640 Least of all Apollo, 199 00:23:45,720 --> 00:23:49,160 who seems to have woken up on the wrong side of the bed. 200 00:23:57,600 --> 00:23:59,320 When he's in a bad mood… 201 00:24:03,200 --> 00:24:07,840 the rest of the group just need to keep their heads down. 202 00:24:26,720 --> 00:24:29,560 He soon finds a target for his rage, though. 203 00:24:40,680 --> 00:24:44,120 Some of the younger chimps have found honey for breakfast. 204 00:24:56,680 --> 00:25:00,240 And they forgot to invite Apollo to join them. 205 00:25:14,640 --> 00:25:19,080 You soon learn, never get on the wrong side of the dominant male. 206 00:25:26,880 --> 00:25:28,400 He's got a nasty bite. 207 00:25:32,280 --> 00:25:34,800 Thankfully, it's not too serious. 208 00:25:43,200 --> 00:25:46,440 With a bit of care, this wound should heal. 209 00:25:49,360 --> 00:25:53,040 But wounds leave behind scars, 210 00:25:54,160 --> 00:25:56,120 etched into the chimps' bodies. 211 00:25:57,400 --> 00:26:03,520 Indelible marks of the past that reveal the one universal truth about time. 212 00:26:07,280 --> 00:26:08,560 It has a direction. 213 00:26:10,640 --> 00:26:13,000 You can never go back in time… 214 00:26:14,640 --> 00:26:17,320 …only forward into the future. 215 00:26:20,800 --> 00:26:22,920 This is time's arrow, 216 00:26:24,200 --> 00:26:27,840 and it leaves scars on everything 217 00:26:28,520 --> 00:26:29,480 across Earth… 218 00:26:31,240 --> 00:26:32,400 …and beyond. 219 00:26:41,160 --> 00:26:46,520 Our moon is pockmarked with battle scars that tell stories of ancient events. 220 00:26:56,480 --> 00:26:57,840 So too are the planets. 221 00:27:01,680 --> 00:27:08,640 Their surfaces testament to a lifetime of bombardment by asteroids and comets. 222 00:27:15,040 --> 00:27:19,120 But perhaps the most impressive impact crater in our solar system 223 00:27:20,680 --> 00:27:23,080 belongs to a moon of Saturn. 224 00:27:24,480 --> 00:27:25,480 Mimas. 225 00:27:27,880 --> 00:27:32,560 The Herschel crater is 130 kilometers across. 226 00:27:38,280 --> 00:27:40,840 Whatever created this enormous scar… 227 00:27:43,000 --> 00:27:46,280 must have come close to shattering the moon to pieces. 228 00:28:04,000 --> 00:28:06,080 Mimas lives to tell the tale. 229 00:28:07,840 --> 00:28:10,400 But events like this are irreversible. 230 00:28:15,320 --> 00:28:19,360 And they differentiate the past from the present. 231 00:28:22,160 --> 00:28:24,600 Impact craters are timestamps 232 00:28:26,360 --> 00:28:28,840 that mark a unique moment in history. 233 00:28:37,400 --> 00:28:40,360 We can never revisit the moment they were created. 234 00:28:43,960 --> 00:28:47,640 But we can piece together traces of past events 235 00:28:49,080 --> 00:28:51,480 and map a course back through time. 236 00:28:56,640 --> 00:28:57,880 Before craters. 237 00:28:59,640 --> 00:29:00,920 Before planets. 238 00:29:01,840 --> 00:29:03,080 Before stars. 239 00:29:05,000 --> 00:29:07,680 Back to a time before time. 240 00:29:14,400 --> 00:29:17,400 Our universe had a beginning. 241 00:29:21,840 --> 00:29:24,960 A very big bang… 242 00:29:27,360 --> 00:29:29,800 that created three-dimensional space 243 00:29:31,280 --> 00:29:32,560 and time. 244 00:29:36,880 --> 00:29:40,240 But space and time are not separate. 245 00:29:41,800 --> 00:29:44,840 Time is woven into the fabric of the universe. 246 00:29:49,240 --> 00:29:54,120 Bound to space as our universe's fourth dimension. 247 00:29:56,480 --> 00:29:59,400 The Big Bang set the universe's clock ticking. 248 00:30:02,920 --> 00:30:05,280 Propelling everything into the future. 249 00:30:09,040 --> 00:30:13,040 It created the arrow of time. 250 00:30:18,640 --> 00:30:21,960 From our universe's very first moments… 251 00:30:32,360 --> 00:30:34,640 …it pushes us all into the future, 252 00:30:35,720 --> 00:30:38,200 causing everything to grow, 253 00:30:39,640 --> 00:30:40,480 age… 254 00:30:42,440 --> 00:30:43,400 …and change. 255 00:30:45,560 --> 00:30:47,000 From childhood… 256 00:30:48,000 --> 00:30:49,120 …to adulthood, 257 00:30:50,400 --> 00:30:54,080 we all travel through life in the same direction. 258 00:30:55,640 --> 00:30:58,320 Getting older day by day. 259 00:30:59,960 --> 00:31:02,800 And with age comes wisdom 260 00:31:04,200 --> 00:31:07,640 as youthful innocence is replaced by experience. 261 00:31:13,120 --> 00:31:17,520 Time's arrow leads us through these stages of life. 262 00:31:21,880 --> 00:31:23,080 It shapes us. 263 00:31:25,760 --> 00:31:27,440 Defines who we are. 264 00:31:31,000 --> 00:31:32,520 From our first moments… 265 00:31:34,680 --> 00:31:35,800 to our last. 266 00:31:41,880 --> 00:31:44,480 Chimps rarely live past the age of 40. 267 00:31:49,200 --> 00:31:50,840 Nothing is immortal. 268 00:31:58,480 --> 00:32:03,240 Everything that exists in our universe has a finite lifespan. 269 00:32:08,680 --> 00:32:11,960 Including, perhaps, the universe itself. 270 00:32:19,600 --> 00:32:23,440 Today, the galaxies are filled with stars. 271 00:32:27,280 --> 00:32:33,600 But 95% of stars that will ever exist have already been born. 272 00:32:38,800 --> 00:32:41,400 So, as our universe journeys into the future… 273 00:32:42,800 --> 00:32:44,080 …the stars… 274 00:32:44,760 --> 00:32:47,800 -…one by one, will blink out… 275 00:32:50,320 --> 00:32:55,200 …leaving the universe to face an ever-darkening future, 276 00:32:56,880 --> 00:32:58,680 stretching out for trillions, 277 00:32:59,400 --> 00:33:02,920 that's thousands of billions, of years. 278 00:33:09,400 --> 00:33:11,640 The age of starlight 279 00:33:11,720 --> 00:33:16,280 will be followed by a dark age of black holes. 280 00:33:22,920 --> 00:33:27,840 These monsters feed on the remnants of dead stars and planets. 281 00:33:29,560 --> 00:33:31,040 And as they do, 282 00:33:31,120 --> 00:33:36,320 their ever-increasing gravity scars the very fabric of the universe. 283 00:33:43,080 --> 00:33:46,400 Distorting both space and time. 284 00:33:48,760 --> 00:33:53,080 The edge of a black hole, called the event horizon, 285 00:33:54,240 --> 00:33:57,400 is a region where gravity has become so strong 286 00:33:58,240 --> 00:34:03,880 it causes time to slow down practically to a standstill. 287 00:34:08,960 --> 00:34:12,280 But even black holes can't escape time's arrow. 288 00:34:15,040 --> 00:34:16,920 In the far, far future… 289 00:34:21,080 --> 00:34:24,360 …when there are no stars or planets left to consume, 290 00:34:25,920 --> 00:34:27,600 they will begin to starve. 291 00:34:32,800 --> 00:34:34,000 And slowly… 292 00:34:36,680 --> 00:34:37,920 very slowly, 293 00:34:39,720 --> 00:34:40,840 they will shrink. 294 00:34:46,360 --> 00:34:48,000 When they die, 295 00:34:48,080 --> 00:34:50,400 no one truly knows what comes next. 296 00:34:52,920 --> 00:34:57,960 But it could be the end of our universe. 297 00:35:07,400 --> 00:35:11,760 Here on Earth, none of us can slow the passage of time. 298 00:35:16,000 --> 00:35:20,280 And one of Celeste's aunts is reaching the end of her time. 299 00:35:24,280 --> 00:35:28,040 Retreating from the group, she heads into the forest alone. 300 00:35:35,800 --> 00:35:37,840 She has lived many years. 301 00:35:41,200 --> 00:35:44,080 But this day will be her last. 302 00:36:03,760 --> 00:36:06,520 While the world continues to spin, 303 00:36:07,920 --> 00:36:11,040 her body lies still. 304 00:36:23,320 --> 00:36:26,160 But time doesn't just carry us toward endings. 305 00:36:30,360 --> 00:36:32,400 It also creates beginnings. 306 00:36:37,280 --> 00:36:40,760 As days turn into weeks and weeks into months, 307 00:36:42,560 --> 00:36:45,600 there are big changes for one special chimpanzee. 308 00:36:59,600 --> 00:37:01,480 Say hello to Cosmo. 309 00:37:06,040 --> 00:37:08,960 Her brain and limbs are now fully formed. 310 00:37:10,720 --> 00:37:13,400 And her eyes are ready to see the world. 311 00:37:21,880 --> 00:37:24,960 The exact timing of her birth is impossible to know. 312 00:37:26,560 --> 00:37:29,400 But she could be born any day now. 313 00:37:36,000 --> 00:37:38,760 She's been in the womb for eight months. 314 00:37:40,240 --> 00:37:43,480 But her journey began long, long ago. 315 00:37:46,000 --> 00:37:50,600 The elements that made her came from dying stars. 316 00:37:52,520 --> 00:37:58,320 The water that flows through her body came from distant worlds. 317 00:38:00,400 --> 00:38:06,920 The energy that powers her muscles came from the heart of our sun. 318 00:38:09,720 --> 00:38:13,040 But it's that most mysterious ingredient, 319 00:38:13,720 --> 00:38:18,200 the one that started ticking 13.8 billion years ago… 320 00:38:22,280 --> 00:38:26,800 that has led all other ingredients to this moment. 321 00:38:30,120 --> 00:38:31,240 In this place. 322 00:38:33,960 --> 00:38:35,200 On this planet. 323 00:38:44,720 --> 00:38:47,920 Another sunrise, another morning. 324 00:38:53,240 --> 00:38:57,520 And this one is extra special. 325 00:39:08,120 --> 00:39:10,520 Welcome to Earth, Cosmo. 326 00:39:15,440 --> 00:39:18,680 This precious moment will never be repeated for Celeste. 327 00:39:19,480 --> 00:39:22,760 But Cosmo's journey has just begun. 328 00:39:26,000 --> 00:39:28,280 It will take around three months 329 00:39:28,360 --> 00:39:32,040 for her body clock to synchronize to the rhythm of the planet, 330 00:39:33,840 --> 00:39:36,400 one year before she can truly communicate, 331 00:39:38,080 --> 00:39:42,680 and perhaps 15 years until she is fully grown. 332 00:39:45,760 --> 00:39:47,520 So much lies ahead. 333 00:39:56,320 --> 00:39:57,600 Like Cosmo, 334 00:39:58,320 --> 00:40:01,360 our universe is still in its infancy 335 00:40:02,400 --> 00:40:06,640 at the beginning of an unimaginably long lifespan. 336 00:40:08,680 --> 00:40:11,920 We are living in the age of starlight. 337 00:40:14,200 --> 00:40:19,160 A moment when time's arrow has filled the universe with beauty… 338 00:40:22,440 --> 00:40:23,400 …and wonder. 339 00:40:32,360 --> 00:40:34,520 But it's a brief window of time 340 00:40:35,440 --> 00:40:39,200 that will never be repeated in the history of our universe. 341 00:40:45,320 --> 00:40:47,720 No one can slow the passage of time, 342 00:40:49,080 --> 00:40:50,160 nor should we try. 343 00:40:55,280 --> 00:40:56,920 Because without time, 344 00:40:58,120 --> 00:40:59,480 there would be no now. 345 00:41:06,720 --> 00:41:08,160 No moment in the sun. 346 00:41:17,200 --> 00:41:18,920 No moments, period. 347 00:41:24,600 --> 00:41:25,720 Without time, 348 00:41:27,760 --> 00:41:29,160 there would be no life. 349 00:41:41,320 --> 00:41:44,120 Next in the story of our universe, 350 00:41:45,800 --> 00:41:47,440 Earth's seasons. 351 00:41:48,960 --> 00:41:51,760 Like a mother bear raising her cubs… 352 00:41:53,120 --> 00:41:56,680 …we all experience our planet's yearly transformations. 353 00:41:59,760 --> 00:42:02,280 But what created Earth's seasons? 354 00:42:05,760 --> 00:42:08,840 How are they connected to the formation of our moon? 355 00:42:09,880 --> 00:42:15,680 And why does only our planet have conditions just right for life?